Re: How To Change A Rule

• To: mathgroup at smc.vnet.net
• Subject: [mg32375] Re: How To Change A Rule
• From: Clemens Frey <frey at mathematik.tu-darmstadt.de>
• Date: Thu, 17 Jan 2002 02:23:27 -0500 (EST)
• Organization: TU Darmstadt
• References: <a20mon\$4hf\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

you may use a simple transformation with a conditional pattern.
Having a list of rules named rlst:

IN[1]:= rlst = {s1 -> -11, s2 -> 12}

then the following

IN[2]:= rlst2 = rlst /. Rule[x_, y_ /; y < 0] -> Rule[x, 0]

sets rlst2 to be the following list of rules:

OUT[2]= {s1 -> 0, s2 -> 12}

Hope that helps.

Clemens

Ariel Fligler wrote:
>
> Greetings,
>
> I'm quite newby to Mathematica programming and will thank you if you could
> help me solve the following:
>
> I have a list of rules of the form:
> {s1->-11, s2->12}
> And would like to change every rule in the list that it's RHS is negative to
> 0 so that I will get:
> {s1->0, s2->12}
> I tried to find an access function to manipulate rules but could not.
>
> Any help ?
>
> TIA,
>
> Ariel.
>
> Thanks,
>
> Ariel Fligler

--
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